This invention relates to improvements in the construction and manufacture of posts and, more particularly to the construction and manufacture of fence posts and highway posts.
For many years, various attempts have been made to make fence and road type posts, as well as other types of post and marker devices, from plastic materials as illustrated by the following U.S. Pat. Nos: Lach 2,821,365; Bellamy 2,976,346; Pilbouis 3,080,149; Byrd 3,091,997; Baumeister 3,378,967; Cuthbert 3,385,565; Blease 3,700,213; Ebinger 3,709,112; Loch 3,720,401; Hellerich 3,740,024; Bartlett 3,776,522; Weichenrieder 3,802,135; Lamarre 3,875,699; Russo 3,891,189; Fornells 3,910,561; Murphy 3,957,250; Deike 4,021,977; Parduhn et al 4,032,248; Schmanski 4,061,535; Minor et al 4,070,007; Ronden 4,078,867; and Humphrey 4,084,914.
Despite the prior effects of others, most commercially acceptable fence posts and highway sign and marker posts continue to be made of T-shaped rigid steel construction. Such posts are relatively heavy and expensive. In highway usage, such posts pose a substantial safety hazard when accidentally struck by vehicles. Such accidents not only can cause substantial damage to the vehicle but may also cause the driver to lose control of the vehicle and, in many cases, the steel posts have punctured the vehicle gas tank leading to fire and explosion. In electric fence post usage on farms and ranches, the conductivity and rigidity of the posts cause problems in the requirements of use of insulator wire mounting devices and in breakage of the wire or disconnection of the wire from the mounting devices under load such as applied by animals against the wire.
While the foregoing problems have been long recognized and the use of plastic materials for posts has previously been suggested, the present invention utilizes the following different concepts than the known prior art:
1. The posts have a monolithic structure made from a suitable thermosetting plastic material or the like.
2. The posts are of solid cross-sectional configuration which may be of relatively small cross-sectional area including cylindrical portions of between 1/2 inch and 2 inches with 3/4 inch to 11/4 inch size being presently preferred for fence line and sign and marker posts while fence corner or anchor brace or other types of posts may be of larger diameter.
3. The posts have integral ground penetration means, stabilization means and driving means integrally molded thereon.
4. The posts have integral attachment devices preferably integrally molded therewith or, alternatively, integrally associated therewith.
5. The posts are flexible under high load while being sufficiently rigid to perform the intended function during normal use.
The post of the presently preferred embodiment of the invention is made of one piece of molded plastic material, polyurethane being presently preferred, comprising: a ground penetrating lower portion; an intermediate stabilizer and driving head portion next adjacent the penetrating portion; and an elongated upper post portion which may have various attachment means thereon such as longitudinally spaced fence wire attachment devices for fence post usage with various kinds of fence wires which may be electrified or sign and/or reflector devices for road sign and marker usage.